The ImageQueue class provides methods for enabling the queue mode for existing image memory sequences. New images will be added to the end of the queue on arrival (FIFO principle). The image memory sequence has to be created with Add().
Image memories in a sequence with queue mode are automatically locked. The image memories will have to be unlocked with Unlock() in order to be re-used in the sequence.
Note that also image capture errors are added to the image queue like images If a call of IS_IMAGE_QUEUE_CMD_WAIT returns the IS_CAPTURE_STATUS return value then you can check by a new call of the function, if any further images were enqueued into the image queue after the error.
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Image memory sequences can also be used without queue mode. In this case the current image memory has to be queried with GetActive() on every frame event. Disadvantage of this proceeding is that at very high frame rates it may happen that additional images arrive between the frame event and accessing/locking the memory. The images arriving in this period will be skipped when you query the current image. When the queue mode is used (Init()), however, you can be sure to always receive the oldest image which has not yet been queried. In addition, image memories are automatically locked immediately after receiving the image. This prevents images from being overwritten when very high frame rates and few image memories are used. |
Methods
Method |
Description |
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Cancels waiting for all operations started with Wait() for the next image before timeout. |
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Discards the oldest N entries in the queue. |
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Deinitializes an internal queue and discards all information about the order of the queued images. |
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Clears the image memories that are currently in the queue. |
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Returns the number of image memories currently in the queue. |
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Initializes a queue mode for an existing image memory sequence. |
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Returns the sequence memory ID of the first (i.e. oldest) image in a memory sequence. |
